Childhood elevated blood pressure (BP) has emerged as a concern for global public health. In Sub-Saharan African countries, where Rwanda is located, there is a scarcity of BP data for both children and adolescents. Elevated blood pressure (EBP) is a neglected issue in children, it can develop in young age and can last into adulthood. This community-based cross-sectional study in rural Kayonza, Rwanda investigated the prevalence and determinants of elevated blood pressure (EBP) in children aged 36 months. Measurements of blood pressure and height were converted to percentiles using World Health Organization standards. Data collection involved face-to-face interviews with a digital questionnaire. OMRON HBP-1320 blood pressure monitor and SECA 213 stadiometer were used. The mean systolic blood pressure was 90.60 mmHg and 58.75 mmHg and standard deviation of 7.60mHg for diastolic blood pressure. Most child's mothers (76%) were farmers, more than half (62.7%) of child mothers attended primary school, and 36.60% were between the ages of 31 and 35. (Mean age: 30.4 years, Stand. Dev.: 4.4, Minimum age: 21 years and Maximum age: 39 years), (53%) of children were males, 38 % were 36 months old (Mean age: 36.9 months, Stand. Dev.: 1.0, Minimum age: 35 months, and Maximum age: 39 months). Elevated BP for children is defined as being prehypertensive and hypertensive; all children with systolic or diastolic blood pressure percentiles of ≥90th to <95th were prehypertensive, while those with systolic or diastolic blood pressure percentiles of ≥95th to 99th and above were hypertensive. The prevalence of elevated BP was 40.4% with 18.6% being prehypertension and 21.8% being hypertension among 3-year-old children in the rural Kayonza district. Of them 72 (97%) children who had elevated blood pressure, their family were using biomass fuel and 71(36.60%) of study children were below the 5th percentile of height which an indicator of short stature, 27(40.91%) among them had elevated blood pressure. Factors like difficulty getting food on daily basis (food insecurity) (AOR=3.75; 95% CI: [1.70-8.27]; p=0.001) and medium monthly family income (AOR= 2.38; 95% CI: [1.07-5.31]; p=0.033) were associated with increased prevalence of elevated BP. No statistically significant was found between elevated blood pressure and prenatal factors. Mobilization and increase community’s awareness on the procedure for measuring children’s BP during routine health visits from 3 years old should be done to prevent this increasingly common health condition which is ignored and in asymptomatic nature. Keywords: Elevated Blood Pressure, Prehypertension, Hypertension, Prenatal Factors, Environmental Factors, Behavioural Factors, Kayonza District, Rwanda.